Portable electric tool



April 1931- o. P. WODACK 1,803,307

PORTABLE ELECTRIC TOOL Filed Aug. 15, 1925 2 Sheets-Sheet 1' Tn vcnib'r0.5 can Z00 61141010,

0. P. WODACK PORTABLE ELECTRIC TOOL April 28, 193:].

2 Sheets-Sheet 2 Filed Aug. 13, 1925 Patented Apr. 28, 1931" PATENTOFFICE OSCAR P. WODACK, CHICAGO; ILLINOIS, ASSIGNOR TO WODACK ELECTRICTOOL GOR- POBA'IION, OI CHICAGO, ILLINOIS, A CORPORATION OF ILLINOISron'rAistn ELECTRIC .TooL

Application flled August 13, 1925. Serial No. 49,930.

My invention relates to improvements in electric tools and hasparticular reference to portable-tools such as are used for drilling orbreaking up stone, concrete and the like.

' The general object of the invention is to provide an electric toolwhich can be manufactured on a very economical basis and which iseflicient and reliable in operation.

A more specific object is to provide a novel means for applying powerderived from an electric motor to the actuating spring of a workingtool.

Further objects and advantages will become apparent form the followingdetailed description taken in connection with the accompanying drawings,in which:

Figure 1 is an elevational view of a tool embodying the features of myinvention.

Fig. 2 is a fragmentary view in vertical section of the tool shown inFig. 1.

Fig. 3 is a sectional view taken along the line 3-'3 of Fig.2.

Fig. 4:.is a view taken along the line 4-4 of Fig. 1.

Figs. 5 and 6 aresectional views along the lines5-5 and 6-6 respectivelyof Fig. 2.

While I have shown in the drawings and will herein describe thepreferred embodi ment of myinvention, I- do not intend to be limitedthereby to the particular form disclosed, but aim in the appended claimsto cover all modifications and alterative constructions falling withinthescope of the invention.

W5 Referring to the exemplary embodiment of the invention illustrated inthe drawings, 10 represents a tubular body or casing defining a chamberin which a plunger 11 reciprocates. Theupper end of the casing is closedby a suitable plug 12 and isfitted with the usual operating handlel3which may be secured to the casing in any preferred manner. Interposedbetween the plug 12 and the plunger 11 is a strong coiled spring 14 dwhich is periodically compressed and then released to supply energy tothe plunger dur ing its working stroke as will presentlybe described. Ia

. The lower end of the casing 10 is fitted with a suitable operatingtool 15 against which the plunger strikes at thefend of its workingstroke. In the present instance a removable cap 16 is threaded on theend of the casing to receive the shank 17 of the tool and retain it incentered position. Preferably the shank 17 is surrounded by a'coilspring 18 extending between the cap 16 and a movable collar 19, whichspring serves to sustain and cushion the blows of the plunger when thetool is running idle.

' Power to compress the actuating spring 14 is derived from a suitableelectric motor 20 mounted adjacent the casing 10 in any preferredmanner. In the present instance the motor is supported by a housing 21with the axis of a shaft 22 extending parallel to the casing 10. To thisend the motor casing is formed with a flange 24 which may be suitablysecured to the housing by screws 25, a bearing plate 26 being placedbetween the two parts. The housing 21 in the form shown herein encirclesthe casing 10 and is removably clamped thereto by screws 27 extendingbetween lugs 28 formed on split portions of the housing. 29 is anintegral lug clamped to the casing 10 and joining the upper end of themotor casing with the casing 10 Thus, it will be observed that thecasing 10, the housing 21. and the motor 20 can be readily disassembledto permit cleaning or repairing of the operating parts of the tool.

To sustain the end and thrust of the motor shaft both of its ends are ofreduced diameter so as to provide shoulders 30 which abut against theends of suitable thrust bearings 31. 32 is a suitable control switch forthe motor. l

Means is provided for applying the power of the motor to periodicallycompress and re lease the actuatin spring 14. This means constitutes animportant feature of the present invention and comprises a worm 33 and a'worm wheel 34 connecting the motor shaft with a toothed wheel. 35within the housing 21. The toothed wheel and the worm wheel are bothkeyed to a shaft 36 which is journalled at its opposite ends in bracketarms 37 integrally formed on the bearing plate 26. The worm 33 is fixedto the lower end of the motor shaft in mesh with the worm wheel. 38

(see Fig. 5) indicates an extension of the forward arm 37 providing abearing support for the extreme lower end of the motor shaft. By thisarrangement the toothed wheel 85 will rotate continuously at a muchslower speed than the motor shaft and with a correspondingly greateramount of power available for each revolution. The worm and worm wheelconnection lends itself readily to the accomplishment of this result andpermits of a compact and simple arrangement of the parts.

On rotation of the toothed wheel 35 in the direction indicated in Fig.2, each of its teeth will be projected through a slot 39 in the easing10 into a longitudinal groove 40 in the plunger for a certain portion ofeach revolution. During this movement the straight edge of each toothwill engage a shoulder 42 thereby causing the plunger to be raised andthe spring 14 to be gradually compressed. As a tooth moves out of theplunger chamber, the spring will he suddenly released and the energystored therein will be applied to the plunger which at that instant willbe free to move downwardly to strike the tool shank 17. By the time theplunger has completed its working stroke, another tooth will have movedinto the casing 10 and will be ready to engage the plunger for thereturn stroke. This cycle of the plunger will be repeated for each toothon the wheel 35.

As a means for preventing mutilation of the parts in case the spring 14should break and the toothed wheel continue its operation, I provide asafety device in the form of a screw 43 extending into the groove 40.This screw is adapted to engage a shoulder 44 and thereby prevent themovement of the plunger any substantial distance beyond the normal limitof its return stroke. The screw 43 also serves to prevent turning of theplunger within the casing in case one of the teeth on the wheel 3ishould break off.

The shoulders 42 and .14 defining the ends of the slot 40 are preferablyspaced equidistant from the ends of the plunger. Thus, when the shoulder42 becomes worn, the plunger may be removed and reversed so that theunworn shoulder 44 will then be in posi tion to be engaged by thetoothed driving wheel.

It will be noted that in the arrangement which I employ natural coolingof the motor windings is not provided for. I have, therefore, mounted asuitable exhaust fan impeller on the motor shaft just above the bearingplate 26. This fan is adapted to draw air through perforations 45 in thetop of the motor casing and deliver it through a flexible tube 46 to anozzle 47 secured to the working tool 15. The fan thus effects a forcedcooling of the motor and serves to blow away chips and dust accumulatingaround the tool.

It will be apparent that the tool which I have provided is of extremelyrugged eonstruction and capable of withstanding the wear and tearincident to the service use of a device of this kind. It comprises aminimum number of parts which are compactly arranged and adapted to bereadily disassembled for replacement or repair. Because of itssimplicity and the advantageous arrangement of its parts, the tool canbe manufactured and operated at a very low cost.

I claim as my invention:

1. In a portable electric tool, a casing, a plunger adapted toreciprocate therein, a spring acting on said plunger, a rotary actuatingdevice adapted to engage said plunger and compress said spring, anelectric motor for driving said actuating device, a housing mounted onsaid casing, and a member removably supported upon said housingincluding supporting means rigid therewith and projecting therefrom intosaid housing for supporting said actuating device in said housing.

2. In a portable electric tool, a casing, a plunger adapted toreciprocate therein, a spring acting on said plunger, an actuatingdevice adapted to engage said plunger, a housing mounted on said casing,a plate removably mounted on said housing, bracket arms depending fromsaid plate and rotatably supporting said device within said housing, andan electric'motor for driving said actuating device.

3. A portable electric drill having, in combination with a casing and aplunger adapted to reciprocate therein, a housing on said casing, a pairof bracket arms removably supported by and projecting into said housing,an actuating device for said plunger rotatably supported by said bracketarms, an electric motor, and a worm and worm wheel driving connectionintermediate said motor and said actuating device.

4. A portable electric tool having, in combination, acasing, a plungeradapted to reciprocate therein, a housing removably mounted on saidcasing, an electric motor mounted on said housing, a plate removablyheld between said motor and said housing, bracket arms depending fromsaid plate, a shaft mounted on said brackets, an actuating device forsaid plunger rigid on said shaft, a worm wheel also rigid on said shaft,and a worm driven by said motor and meshing with said worm wheel foractuation of said device.

5. A portable electric tool having, in combination, a spring hammer witha longitudinally slotted cylindrical casing, a hammer and an actuatingspring inside casing, a housing secured on the side of said casing andcommunicating with the slot in the casing, a motor, speed reductiongearing connected to said motor. and mounted within ahousing, and a starwheel driven by said gearing and engageable with said hammer to actuatethe same, said star wheel being mounted in said casing to permit removalof the star Wheel from the housing While the hammer is assembled andwhile the housing is in position on said casing.

In testimony whereof, I have hereunto affixed my signature.

OSCAR P. WODACK.

